NRF52840 SPI transfer buffer length

RE: NRF52840 SPI transfer buffer length

AlexW — Wed, 19 Jun 2019 13:20:37 GMT

Hi,

I am using SDK 15.3 and function nrf_drv_spi_transfer and the SPI buffer length are still limited to 255 (unit8_t).
Unfortunately changing the type to uint16_t in the function definition does not work. SPI transmissions larger that 255 byte still won't work.

Can you suggest what I have to change to get it work?

I am using nrf52840 and nrf52832.

Thanks, Alex

RE: NRF52840 SPI transfer buffer length

Jakub Rzeszutko — Tue, 22 May 2018 06:13:22 GMT

Hi,

Transfers longer than 255 bytes can be realized using nrfx functions. It is not implemented in legacy driver. I expect that changing buffer length in legacy driver may not be enough.

For sure the newest revision of nrf52840 will have buffers 16 bytes long.

RE: NRF52840 SPI transfer buffer length

alasknnj — Mon, 21 May 2018 20:18:11 GMT

Jakub Rzeszutko is it possible to send more than 255 bytes now? The SPI transfer function still only accepts uint8_t. If I change that to uint16_t, should it work? I observed that all other transfer functions, which use the nrfx_spim_xfer_desc_t, use size_t instead.

I also found here that the engineering A has can't be set with 16 bit for the TXD.MAXCNT register, is that really true? DOes that work for Rev 1?

RE: NRF52840 SPI transfer buffer length

Jakub Rzeszutko — Fri, 09 Feb 2018 06:22:06 GMT

Hi,

Yes you can increase the size of your transfer buffer, we will update it in comming SDK15.